Electrical indicating apparatus



Juiy 28, 1936s J. A. PRocToR ELECTR CAL INDI CATING PPARTUS Original Filed Sept. 4, 1920 2 Sheets-Shea?. l

Ilflllll INVENTOR, John /P/*focm' ATTORNEY July 28, 1936. J. A. PROCTOR 2,048,814

ELECTRICAL INDICATING APPARATUS Original Filed Sept. 4, 1920 2 Sheets-Sheet 2 INVENTOR, cfolz A .Prociong ATTORNEY Patented July 28, 1936 PATENT OFFICE s 2,048,814 ELECTRICAL INDICATING APPARATUS John A. Proctor, Lexington, Mass., assigner, by

mesne assignments, to General Electric Company, a corporation of New York Original application September 4, 1920, Serial No. 408,291. Patent No. 1,555,254, dated September 29, 1925. Divided and this application August 19, 1925, Serial No. 51,267

21 Claims.

Ifhis applicationis a division of the application for my Patent 1,555,254 granted September 29, 1925.

The invention relates to apparatus, as in radio telegraphy and telephony, wherein there is produced a continuously variable eect involving a change in electrical conditions, by the movement of an actuating handle or rotating device, and whereby in electrical circuits or net-work in m general or any other apparatus the operations of a plurality of independently movable elements are coordinated, particularly in respect of an indicating device having relatively movable parts.

An object of the invention is to provide a mechanical means which makes possible the linking of variable elements, including the movable member of an indicating device, in such a way that, by the movement of a single turning meml ber, these elements may be varied in proper relation to one another to maintain the adjustment.

Specifically, the present invention relates to electrical apparatus (including variable air condensers as commonly used in receivers in radio telegraphy and telephony) which has a rotatable conductor system or element and a circular indicating scale marked with divisions forthe vari-A ous positions of the rotating conductor system with respect to another conducting system or element more or less remote therefrom, such as the fixed plate system of a variable air condenser. In any such apparatus various diierent electrical effects are produced at the diilerent relative positions of the relatively movable conductor systems, such as various different electrical capacities in a variable air condenser, depending upon the design or construction of the rotatable condenser plate system and its neighboring stationary plate system.

A feature of the present invention, therefore, consists generally of the interposition of a inemoptimum ber between the rotating conductor element or system and the movable member of the indicating device, such interposed member being bendable and bent into and operably maintalnable in a shape producing desired positions of the movable indicator-member for the various angular positions of the simultaneously rotated conductor system, such positions of the indicator-member being predetermined by bending said interposed member, pursuant to observed electrical effects of the conductor system in different angular positions thereof, into a curve which causes the desired indications at the various angular (Cl. Z50- 40) positions of the conductor system. Specifically, this feature of the invention is shown as embodied, for illustrative purposes, in'a variable air condenser, preferably in a form wherein the scale of the indicator is marked with equally spaced divisions.

The invention is made clear by reference to the drawings, of which Fig. 1 is a plan of one of the various practical embodiments;

Fig. 2 is a similar view of the same, but here some of the interior parts are illustrated by dotted lines; and

Fig. 3 is a central vertical section of the same, along line 3--3 of Fig. 2 and looking in the direction of the arrows of Fig. 2.

Fig. 4 shows diagrammatically my condenser connected across the inductance coil of a wave meter or that of a radio receiver.

As illustrated, by way of example in these drawings, this particular embodiment of the invention comprises a cover-plate a, rotatably mounted on a fixed plate b, which is secured to a casing c within which may be mounted a variable capacity. On the inner surface of the cover-plate a, there are mounted a plurality of adjusting screws N, to which is secured the exible plate i.

The movable element of the variable capacity may be mounted, in this instance, on a shaft d, which projects thru the plate b, and carries at its outer end a pinion e, which meshes with a rack f, cut on the side of a flat bar g, which is slidably mounted on the plate b.

The bar g is provided with two rollers, h, h, between which the flexible plate is adapted to pass. It will now be seen that the flexible plate i, bar g, and rollers h, h, together with rack f and pinion e, constitute a gearing system in which variable rotation is imparted to the rotative element by 'a uniform rotation of the cover plate or controlling member a. The member i is essentially a component part of the gearing system, as by virtue of its variability in contour and its connection with the rack and pinion members,` a uniform rotation of the cover plate or controlling member a is adapted to impart variable rotation tothe rotor shaft dof the condenser. The cover-plate a is provided with a handle i, with which to rotate it, and an opening K, thru which a scale l, marked on the plate b, is visible. s

The movable member or index of the indicating device may be, as shown in Figs. 1-2, the

rotatable cover-plate a itself, which is provided with the index markings shown at the edge of window-opening K, so as to be alongside the semi-circular division markings on stationary scale-member l below it, the latter being marked with one hundred and eighty equally spaced divisions, as shown; so that plate a with its index markings functionally is an index, pointer or needle constituting the movable member of the indicating device, and turning to left and right over scale I, bringing window-opening K over various parts of the scale, and causing the index markings on device a to point to the various scale divisions on scale-member l which show thru window K.

By glancing at Fig. 3, one can readily see that a movement of the handle j, carrying with it the curvedstrip i, will cause said strip to pass between rollers h, h., causing movement of said rollers and their support (bar y, and rack f), and consequently causing, via pinion e, a rotation of shaft d to an extent which is dependent upon and controlled by the shape oi curve i. En other words, one readily reproduces mechanically a capacity curve plotted against movement of conducting plate system d in such a Way that the rate of change of movement of this conducting system can be varied at will.

In effect, therefore, the strip i is in the form of a curve, produced as hereinafter described, pursuant to observed electrical effects of conducter system d in different angular positions thereof, said curve representing relations between systern d and indicator-index a, this curve i, however, being a mechanically functioning part of the indicating apparatus. When my condenser is used to tune the circuit of a radio receiver or Wave meter it may be connected in the usual way to the terminals i, 2 of an inductance coil L, as shown in Fig. 4. When so used it is obvious that the rate of change of capacity of the condenser vfor a given rotation of handle y' dependson the curvature of strip i and that the maximum and minimum capacity values (for given extreme adjusting positions of handle j) depend on the settings of the upper screws N (Fig. 2). The rate of change of capacity between the minimum and maximum values may be adjusted or changed at will to any desired value by the proper relative adjrwtment of the tive intermediate screws N. What is here said with respect to changes in capacity of the 'condenser applies as well to the changes in resonant frequency of the circuit, including coil L, in which the condenser is connected.

This mechanical arrangement is adaptable to a variable condenser in such a way that the capacity variation brought against movement of the handle 1' can be made to assume a straight line, or, in other words, the movement of index a over scale I graduated in equal units will produce an equal variation in capacity for each unit or scale division.

Adoption of this device for use in calibratng condensers, for use in wave meters and other measuring devices, eliminates the necessity of designing the condenser plates and adjusting them accurately to obtain the desired capacity curve, such curve, as above mentioned, being resident in strip i instead of being controlled initially by the design of the condenser plates.

The drawings illustrate a condenser equipped with a curve arrangement whereby the capacity curve of the condenser relative to the movement oi the handle i may be made to assume any value. This is oi special value in constructing condenser: for wave meter or decremeter circuits, where it is desirable that these circuits be calibrated in wave-length directly, or where the ratio of capacity value of a condenser to a given movement o! the handle may be made to assume any quantity.

By the present invention I am able to coordinate the movements of the rotatable index a of the indicating device with the rotatable conductor system d, by the means such as herein described. I'he relation between the .two movements is a complex one, that is, non-linear, but, by the coordinating means herein described, a given rotation of system d is caused to be accompanied by a desired movement of indicatorindex a irrespective of the complexity of the relation between these movements and notwithstanding that both these elements are simultaneously rotated, altho at different rates, depending upon the curvature of strip or band i.

The member iis a strip of flexible metal which can be bent into the shape of a fair curve, the shape of which can be altered at will and maintained after once having been set by means oi' the adjustment screws N.

From the above description, the general manner of use of the invention readily will be understood to be as follows, taking the above-described specic case, wherein stationary circular scale l of the indicator, is rotatably mounted on stationary scale-plate b via the ball bearings illustrated. In order to calibrate, i. e., determine the desired curvature of strip or band i relative to the divisions marked on scale l, the condenser terminals are connected across any well-known capacity meter. For illustration, consider the example shown, wherein scale-member b is marked with scale l in divisions equally spaced apart. In the positions shown in Figs. 1 2, window K exposes a portion of the scale between divisions and 100, and the right-hand end of band i, (not yet set to the desired curvature), secured to right-hand screw N, is located adjacent scale marking 180. With the electrical connections made to the capacity meter, the coverr plate a (constituting the movable index of the indicator) is rotated by handle 1 from the position shown, say clockwise, moving window K over above scale-reading 180, and carrying the right-hand screw N and the adjacent right-hand portion of band i around until that part of band i is located between movable rollers h, h (Fig. 2), which rollers engage the opposite surfaces of band i. Said right-hand screw N then is turned, in one direction or the other,'(or both alternately for trial), until a reading of a capacity-meter indicates a balance at a setting of micromicrofarads. By such turning of screw N, the right-hand end of band i, secured to the said screw, has been moved radially, carrying with it rollers h, h, and rack f, which latter has rotated pinion e and the rotatable conductor system d so that the latter is in such relation to the stationary condenser plates that the capacity of the condenser is 180 micro-microfarads corresponding with the reading of index a on scale l. After such desired turning of screw N to bend the righthand end of band i to the desired position, said screw maintains that part of band i in the position to which it has been bent. Such bending of band i then is repeated at the other six portions ot its length controlled by the remaining six screws N from right to left, the successive capacity settings being, for the six equally spaced screws N, respectively, 180, 154. 128. 77, 53, 26 and approximately zero on the lowest capacity obtainable with a variable air condenser, said numerals referring to the numbered divisions of scale l and the positions thereon 'of index markings on cover-plate a. The oand i thus bent constitutes a record of the observations of the readings oi the meter.

One can readily see that after this curve is established, a movement of the handle y in either direction will allow the capacity of the condenser to be varied according to the shape of the curve and in such manner as to produce the desired scale readings of the indicator at the various angular positions of indicator system d; and that such conditions will be established at all points between the limits of the operation of curve i.

This is true, because the rollers h, h, always will come back to the same positions determined by the initial setting of curve i, and it is true also that these points determine a curve, and experience shows that, if a suitable number of points are taken along a curve, representing, for instance, capacity against mechanical rotation of conductor system d, these points joined in a fair curve will represent the actual relations `in the condenser, and that any points taken between the points of reading will be extremely accurate. This simple mechanical device, therefore, allows a variation of the continuously variable elements d and a in the right proportion to maintain the proper adjustment, so that the condenser capacity can be varied over the limits of the capacity of the instrument by the movement of a single lever or handle, manually or otherwise mechanically operated, to cause the simultaneous rotation of d and a, altho atdiiferent rates, depending upon the curvature of band i.

The indicator-index a will give the desired scale readings at the various angular positions of system d, without any special design or construction of the condenser conductor plates of said system d relative to the stationary condenser con- `ductor plates, and quite irrespective of the nature of said stationary conductor plates or their relation to conductor system d, provided only that said conductor plates be near enough to system d to produce or modify an electrical eiect upon it. Thus, the constructor, furnished with an indicator having any desired scale marking, with exible band i, but with unknown conditions as to the electrical eiect on system d of the neighboring conductors, can produce conditions, by way of band i, which will produce the desired scale readings without any consideration of the relations between conductor system d and the neighboring conductors, or the amplitude ofthe electrical eiect of the latter upon the former. Thus, the band i, controlling the relative rates of rotation of indicator-index a and conductor system d, serves to compensate for the varying effects of the neighboring conductors uponv the rotatable conductor system din the various angular positions of the latter, to which positions the latter is moved atdierent rates from index a i relative to scale I, dependent upon the curvature dicator-index a may be arranged in any desired manner, depending upon the nature ot the apparatus which is to include it, altho. as in the disclosed embodiment in a variable air condenser, it

is preferred to have member i as a movable ele- 5 ment. Likewise. as disclosed in Fig. 11 of my said patent, the conductor system d, as a. condenser plate system, may be replaced, in combination with curved band i, by a conductor system consisting of an inductance coil. Likewise, the simultaneous rotation of d and a may be effected by any desired rotating device, altho, in the example shown, that is done by turning scaleindex a via handle :i mounted upon it, which thereby turns d via curved control member i, it l5 being permissible thus to cause index a to drive conductor system d in an embodiment like the present one, where system d has little inertia and index a is a comparatively strong member, in the form of cover-plate a, rotatably supported at its periphery by the ball bearings of Fig. 3. Also, while the indicator members l and a may have any desired relative rotation, yet it is preferred.` as shown, that scale l be stationary during operation of the apparatus and that index a be the movable member. In any case, the advantage is that 'the relations of indicator a', l, to system d are controlled by bendable curved member i, quite independently of the effect on system d of the electrical conductors in its vicinity, save as such eiect is compensated for denitely and permanently by the initial bending of indicator-control member i under conditions, as above described, when conductor system d is subject to the electrical inuence o! itsneighboring conductors, '8l so as to cause the desired indication to be given by index a at the various angular positions of conductor system d. When, as shown and above described, and as preferred, the scale l comprises equally spaced divisions, the index a. will show on such scale the true conditions relative to conductor system d at the various angular positions thereof, due to the predetermination of the shape of curve i, notwithstanding that such given positions of system d may be angularly diierent from the simultaneous positions of index a as the result of their different rates of rotation by their common rotating device acting via indicator-control band i.

While it is preferred, as shown, to have the scale marked with equal divisions, yet it is clear that the adaptability of exible indicator-control band i is such as'to permit the coordination or compensation to be made with respect to any desired scale marking, on the one hand, as well as with respect to any unknown existing electrical eifects on conductor system d of the other electrical conductors in its vicinity; so that the scale readings may not only indicate the true conditions as to system d, but may provide any arbi- Ci) trary indication which may be desired.

In order fully to explain the invention, and its uses and advantages, the following is added to the above description. The departure of curve i from a true circle is the thing which causes C5 the desired scale readings corresponding with the electrical influence on rotatable conductor system d of all neighboring electrical conductors, notwithstanding that the nature of the latter is not considered in the construction of the appa'- ratus, no attention at all being paid to them save the predetermination of their effect on rotatable conductor system d in its various angular positions by observation of the seeming electrical eiects of the rotatable conductor system 7 itself. Instead of calculating, designing and constructing the stationary and rotatable conductors with relation to one another and to any and all neighboring conductors so as to cause the rotating system to be electrically influenced in a way predetermined in relation to the desired indicator, such indicator and the rotatable conductor system d alone are designed and adopted independently in any desired or convenient form, having only in mind that curve i is to be employed thereafter to control, in accord with the indicator, whatever electrical influence the various neighboring conductors may have upon the rotatable system in the various angular positions of the latter.

'I'he invention provides means for securing an electrical instrument of precision, whatever be the specific nature or purpose of any particular embodiment. In variable condensers, for example, as heretofore produced generally, the

armature plates have been arbitrarily constructed without reference to the capacity at any angular position of the rotor, (notwithstanding that in a few instances the plates have been designed carefully to cause definite capacities), and the indicator has shown an entirely arbitrary scalereading; and even so, the true capacity was liable to be and usually was affected not only by the relation of the armature plates to one another but by other neighboring altho insulated metal parts such as the metal condenser-casing itself,

and by edge effects, etc. In general, any change in capacity by relative movement of the armature plates, has had no definite known relation to the angular relation of the armatures, even in cases where attempts have been made to obtain accurate control and indication by careful design of the relation of the armature plates to one another. But it has been desirable to be able to read on a scale, either true values or at least, values having a definite known relation to the indicator as moved by the rotor in its various angular positions with respect to neighboring electrical conductors of any kind. There are three ways of obtaining such desired result, the third of which involves the present invention. First, the condenser or other electrical apparatus in question can be tested in its various angular relations by comparison with known values, the result of the test at various angular positions, being recorded in the form of a table of figures or a curve sheet or a chart as a record of errors; and thereafter corrections can be made for each reading for the indicator, by way of such record. The disadvantage of that method is that it introduces the possibility of human error in compensating between the indication and the correction-reoord. Second, the scale of the indicator may be left blank until after assembly of the apparatus, the completed instrument being then operated and tested, and the observed results at successive angular positions of the rotor scribed on the scale of the indicator, this in lieu of a. separate record. But in such a method, unless an equal change in electrical conditions was eiIected for the successive equal angular movements for the rotatable conductor system, the resulting scale would of any desired or arbitrary scale, including the important and usually most desired one wherein, as shown, the scale is marked with equal scaledivisions as in degrees of arc. Thus, in lieu of an error record, from which each scale-reading must be corrected, the band i of the present invention is made a functioning part of the rotating apparatus and acts as an automatic errorless compensator between the desired scale readings and any discrepancies due to miscellaneous electrical iniiuences on the rotatable conductor system, the band i being shaped initially in accord with discrepancies actually observed in the operation of the rotating electrical system, and these discrepancies being recorded in the shape of band i as an operating element of the mechanical system instead of in any form of record independent of the apparatus such as a curvesheet, chart or table. Band i altho'capable of being maintained by screws N in operative condition as set, is also capable by its flexibility of being re-set to a modified curvature, upon a showing. by re-test, of any change in surroundlng electric fields. All these considerations apply to various rotatable electrical systems other than the variable condenser shown, for in all variable electrical systems, the mechanical movement involved in the variation very rarely, if ever, is directly proportional to the variation of the electrical ileld, of whatsoever nature, in the space between the rotatable conductor system and any other electrical conductors in its neighborhood, whether they be the rotating conductors intentionally forming part of the apparatus itself, or other conductors fortuitously present, such as the metal condenser casing above mentioned. But in the present invention, curve i serves automatically to compensate for any such ileld which diners from such a perfect neld as may be desired, in that it is distorted in its relation to the desired indicating device by causes not necessary to be determined, in the practice of the invention. All that is necessary, in order to employ curve i is to observe the electrical results or eiIects of such indeterminate causes, and then accordingly bend and fix the curve which constitutes an operating element of the rotatable conductor system.

I particularly point out and distinctly claim the part, improvement or combination which I claim.

as my invention or discovery, as follows:

1. In a variable electrical air condenser comprising a rotatable conductor system and an indicator having a circular scale and a relatively rotatable index, the improvement which consists oi an operating connection comprising a control member, said connector mechanically connecting said conductor system and rotatable indicator member; and a device causing simultaneous rotation, via said control member, of both the conductor system and the indicator member; said control member being bendable; said circular scale being marked with equal divisions; and said control member being bent into and maintained in a curve causing the rotation of the conductor system to produce an equal change in condenser capacity for each movement of the indicator member per division of said scale.

2. In a variable electrical condenser comprising a rotatable conductor system and an indicator having an index member and a relatively rotatable circular scale marked with desired divisions, the improvement which consists o1' an operating connection comprising a control member, saidconnection mechanically connecting said conductor system and rotatable indicator member; and a device causing simultaneous rotation, via said control member, of both the conductor system and said indicator member; said control member being bendable and bent into and maintained in a curve causing the indicator member to be rotated at rates different from that of the conductor system, notwithstanding their simultaneous operation by the rotating device; said curvature being predetermined by observation of the electrical effects accompanying rotation of the conductor system, and said curvature causing the desired scale readings for the various angular positions of the conductor system.

3. In a variable electrical condenser comprising a rotatable conductor system and an indicator having an index member and a relatively rotatable scale marked with the desired divisions, the improvement which consists of an operating connection comprising a control member, said connection mechanically connecting and permitting the simultaneous rotation of said conductor system and rotatable indicator member; said control member being bendable and bent into 'a curve causing rotation of the conductor system to effect a change of condenser capacity having a desired relation to said scale divisions; and devices maintaining said bendable control member operatively in such curved condition.

4. In a variable electrical condenser comprising a rotatable conductor system and an indicator having a rotatable index and a stationary senilcircular scale marked with one hundred and eighty equally spaced divisions, the improvement which consists of an operating connection between the said conductor system and index, said connection including a bendable control band and rollers bearing on the opposite surface thereof and permitting simultaneous rotation of both the said conductor system and index; said band being bent into a curve causing desired scalereadings at the various angular positions of the conductor system.

5. In electrical apparatus comprising a rotatable conductor system and an indicator having a rotatable index and a stationary semi-circular scale marked with one hundred and eighty equally spaced divisions, the improvement which consists of an operating connection between said conductor system and index, said connection including a bendable control band and rollers bearing on the opposite surfaces thereof and permitting simultaneous rotation of both said conductor system and index; an operating device for effecting such simultaneous rotation via said band; the band being bodily movable with said operating device; said band being bent, pursuant to observed electrical conditions in the conductor system at different angular positions thereof, into a curve causing said index to be turned at rates different from that of the conductor system itself, and causing the desired scale-readings at the-various angular positions of the conductor system; and

devices maintaining said bendable band operatively in such curved condition.

6. In electrical apparatus comprising a rotat-v able conductor system and an indicating device having an index anda relatively movable semicircular scale markedl with equally spaced divisions, the improvement which consists of an operating connection between said conductor system and the rotatable indicator member, said connection including a bendable control band and a rolling device bearing on the surface thereof and permitting simultaneous rotation of bothl tions of said conductor system;

said conductor system and indicator member; an operating device for effecting such simultaneous rotation: said band being bent into a curve causing said indicator member to turn at rates different from that of the conductor system and give the desired scale-readings at the various angular able conductor system and an indicating device having a relatively movable index and scale, the latter being marked with desired divisions, the improvement which consists of an operating connection between the said conductor system and the rotatable indicator member, said connection including a bendable control band and a rolling device bearing on the surface thereof and permitting simultaneous rotation of both said conductor system and indicator member; and an operating device for effecting such simultaneous rotation; said band being bent y into a curve causing desired scale-readings at the various angular positions of the conductor system.

8. In electrical apparatus comprising a rotatable conductor system and an indicating device having a relatively rotatable index and scale, the latter being marked semi-circularly with one hundred and eighty equally spaced divisionathe improvement which consists of an operating connection comprising a control member, said connection mechanically connecting and permitting the simultaneous rotation of said conductor system and the rotatable indicator member; said control member being bendable and bent into a curve of desired shape, causing desired scalereadings at the various angular positions of the conductor system; devices for maintaining said bendable member in such curved shape; and an operating device effecting simultaneous rotation of the conductor system and the rotatable indicatorl member but at different rates due to the curvature of said control member.

9. In electrical vapparatus comprising a rotatable conductor system and indicator having an index and a scale, one of which is rotatable and member with the rotatable conductor system and permitting simultaneous rotation thereof, said control member being bendable and bent into a curve causing the turning of the rotatable indicator member relative to the stationary indicator member to be in desired coordinated relation to said conductor system, and causing the desired scale-readings at various angular posiand devices maintaining said bendable control member operatively in such curved condition.

l0. In electrical apparatus comprising a rotatable conductor system and an indicator having a relatively movable index and a scale marked with desired divisions, the improvement which consists of an operating connection comprising a control member, said connection operatively connecting the rotatable indicator member with the rotatable conductor system, permitting simultaneous rotation of both said system and indicator member, said control member being bendable into a curve causing desired scale-readings at various angular positions of the conductor system.

11. In a variable electrical'condenser comprising a rotatable conductor system and an indicator having a rotatable index and a stationary circular scale marked with equally spaced divisions, the improvement which consists of an operating connection between the said conductor system and index, said connection including a curved member and a bearing member engaging the curved member and permitting simultaneous rotation of both said conductor system and index; the rotation of said curved member causing desired scale-readings at the various angular positions of the conductor system.

12. A variable air condenser including a rotatable conductor system, a capacity-indicator having a rotatable member, an operating connection between the rotatable conductor .system and the movable member of the indicator, causing their simultaneous rotation, and a control member having a curvature eiectuating a desired relation between the rates of rotation of the rotatable indicator member and the rotatable conductor system.

13. A variable air condenser which includes a rotatable conductor system, a capacity indicator having an index and a relatively movable scale, the scale bearing equally spaced capacity markings; and operating mechanism simultaneously rotating the conductor system and the rotatable member of the indicator; and a control memlmr formed with a curvature causing different rates of rotation of said rotatable members and eiIecting an equal change in capacity of the condenser for each of the equal divisions of the indicator scale.

14. The combination with an apparatus which includes a rotatable electrical conductor system and a rotatable member of an indicator. of an operating connection between said rotatable elements causing their simultaneous rotation; and a control member formed with a'curvature causing the movement of the indicator member to be directly proportional to the varying electrical effects of the rotating electrical conductor system.

15. The combination with an apparatus including a rotatable electrical conductor system, of an indicator including a relatively rotatable pointer and scale, the scale bearing any desired scale-marking, an operating connection between the rotatable conductor system and the rotatable member of the indicator, causing their simultaneous rotation; and a bendable control member causing diierent rates of rotation of said two rotatable elements.

16. The combination with an apparatus including a rotatable electrical conductor system, of an indicator including a relatively rotatable pointer and scale, the scale bearing any desired indicating-marking; an operating connection between the electrical conductor system and the movable member of the indicator permitting their simultaneous rotation; and a curved record of the electrical operation of the rotatable conductor system, said record being in the form of a mechanically functioning part oi said operating connection and constituting a control member for the'l connecting the controlling member with the movable element for imparting variable movements to the latter from equal extent of movement of the controlling member to produce equal changes in the electrical circuit in which the instrument is used.

18. A condenser comprising two elements relatively movable to vary the capacity thereof, and an operatively connected control member adapted to impart relative movement to the condenser elements to give such variation in capacity that equal increments in the movement of the control member give equal changes in the resonant frequency of a circuit in which a condenser is used.

19. An electrical instrument comprising a stationary element, another element rotative with relation to the stationary element, a controlling member, and gearing having diifering contours to impart variable rotation to the rotative element derived from uniform rotation of the controlling member for changing the constants of the circuit in conformity with the movement of the controlling member in such a manner that equal movements of the control member give equal changes in the resonant frequency of the circuit in which a condenser is used. Y

20. In a wave signaling system, the combination of an inductanoe coil. a tuning condenser having means for varying the capacity thereof,

said coil and condenser being connected together' to comprise an oscillatory circuit, and frequencyadjusting means for said circuit whereby the maximum resonant frequency of said circuit and the rate of change of resonant frequency of said circuit may be adjusted supplementally of said means for varying the capacity of said condenser.

21. In a wave signaling system, the combination of an inductance coil, a tuning condenser having means for varying the capacity thereof, said coil and condenser being connected together to comprise a tuning circuit, and adjusting means for said circuit whereby the maximum resonant frequency of the circuit and the rate of change of resonant frequency of the circuit may be adiusted supplementally of said means for varying the capacityl of said condenser.

JOI-m A. PROCTOR. 

